A suicide bomber rammed an explosives-laden car into a minibus carrying Afghan soldiers in a crowded market south of Kabul, killing at least 13 people and wounding 20, officials said. The Taliban claimed responsibility. The third suicide blast around the capital in eight days was in line with the militants' strategy of staging spectacular attacks on Western-trained security forces, but civilians usually pay the highest price. The bomber's car struck the minibus full of troops Wednesday at a bustling market, said Aziz Ahmad, an Afghan army officer at the scene. Officials said six soldiers and seven civilians - including four children - were killed. Seven other soldiers and 13 civilians were wounded. A purported Taliban spokesman, Zabiullah Mujaheed, claimed the Islamic militant group staged the blast. In a text message to an Associated Press reporter in neighboring Pakistan, Mujaheed identified the bomber as Abdul Rahman, a resident of eastern Khost province. A series of attacks in recent months has targeted buses carrying Afghan security forces, a key element of US efforts to beat back the insurgency gripping the country's south and east. On Sept. 29, a suicide bomber blew himself up in an army bus in Kabul, killing 28 soldiers and two civilians. In June, a bomb ripped through a bus carrying police instructors in Kabul, killing 35 people. Militants have conducted at least 133 suicide attacks this year, a record. At least 6,200 people have died in insurgency-related violence in 2007, also a record, according to an AP tally of figures from Afghan and Western officials. Suicide attacks often target international and Afghan security forces, but most of the casualties are civilians. Wednesday's bombing came a day after one against a NATO convoy injured 22 civilians. The minibus' mangled frame lay on the roadside as the wounded were rushed to hospitals. Mohammad Amin, who runs a nearby bakery, said flying glass wounded two of his employees. "Every day this bus stops in front of my bakery to take employees of the defense ministry," he said. "Suddenly today, a very strong explosion hit the bus." Mohammad Akram said his sons, 13 and 8, were praying in a mosque when they were wounded by metal and glass from the explosion. Separately, an Afghan army patrol killed 10 Taliban fighters during a clash in southern Zabul province after the militants set up a checkpoint on a main highway, said Abdul Raziq, a provincial army commander. In Helmand province, US-led coalition troops killed several Taliban militants during raids on compounds in Garmser district, a coalition statement said.